Bobbin case



July 10, 1956 F, 5, HOWARD 2,753,825

BOBBIN CASE Filed Sept. 11, 1952 2 Sheets-Sheet 1 Jiig 2.

F. S. HOWARD BOBBIN CASE July 10, 1956 2 Sheets-Sheet 2 Filed Sept. 11, 1952 Wa7z% i awav d,

Unitd 81331168 2,753,825 BOBBIN CASE Frank S. Howard, Chicago, 111., assignor to Birtman Electric Company, a corporation of Illinois Application September 11, 1952, Serial No; 30 9 ,0l 1 Claim. (Cl. 112'-231) This invention relates to a sewing machine and particularly to a bobbin case for removably retaining the bobbin therein.

In rotary hook sewing machines the loop forming beak is rotated in timed synchronization with the reciprocation of the needle to cast a loop formed from the needle thread around the bobbin thread in forming the lock stitch seam. The bobbin with the thread wound thereon is ordinarily rotatably retained in a bobbin case which in turn is positioned within the rotatable hook.

As the rotary hook and bobbin case are located immediately beneath the needle in the bed of the machine, it is ordinarily difficult to remove the bobbin from i'ts case when it becomes necessary to substitute a filled bobbin for an empty one. This is true because of the limited space and because ordinarily only one or two fingers can be used in manipulating the bobbin case and removing the bobbin therefrom.

Various latching means have been proposed for removably retaining a bobbin within the bobbin case. These have ordinarily employed lever systems which required manipulation in order to separate the parts of the bobbin case preparatory to removing the bobbin therefrom. Furthermore, as a latching mechanism had to be kept relatively tight in order that lo'oseness would be avoided, opening and closing these latches were often quite difiic'ul't.

The bobbin case of this invention successfully solves the problems of providing a bobbin case that is easily opened yet is secure enough to retain the bobbin in position by providing a bobbin case comprising a cupshaped body section, a cap section telescopically received in the body section for retaining a bobbin therebetween and a snap-acting spring catch member on one section cooperating with a catch receiving portion in the other section for removably connecting the sections together.

The invention will be described as related to the embodime'nts shown in the accompanying drawings. Of the drawings:

Figure 1 is a fragmentary side elev'ational view of the head of a sewing machine embodying the invention with the bed of the machine partly in section.

Figure 2. is a sectional elevation taken substantially along line 2-2 of Figure 1.

Figure 3 is an enlarged front elevational view of the rotary hook and the bobbin case therein.

Figure 4 is a sectional elevation taken substantially along line 4'4 of Figure '3.

Figure 5 is a -rear elevational' View of the bobbin case of Figures 3 and 4.

Figufe 6 is a from 'el'evatiohat view Of a bobbin case 2,753,825 Patented July 10, 1956 2 and bobbin illustrating a second embodiment of the invention.

Figure 7 is a sectional elevation taken substantially along line 7'7 of Figure 6 The sewing machine shown in the accompanying drawings comprises a bed plate 10, a standard 11 arising therefrom, a substantially horizontal arm 12 at the top of the standard 11 and extending outwardly therefrom and a head 13 on the outer end of the arm 12.

The standard 11 is provided with a variable stitch regulating mechanism adjustable by means of a lever 14 as is customary in sewing machines of this type. At the top rear portion of the arm 12 there is provided a spool receiving spindle 1 5 extending upwardly therefrom. The head 13 of the machine is provided with a reciprocable thread take-up lever 16, an adjustable thread tensioner 17, a hold-down foot mounted on the end of a vertical bar 19 and a needle 20 removably retained on the lower end of a reciprocal vertical needle bar 21. These elements are all customary in household type sewing machines and perform their usual functions. Thus the needle is reciproeated by means of the bar 21 to form the stitches while the hold-down foot 18 cooperates with feed dogs 22 in feeding material beneath the needle 20. The foot are arranged to be driven in the usual four motion move-.

merit. Thus extending downwardly from Within the standard 11 and into the bed of the machine beneath the bed plate 10 is an essentially vertically reciprocal rod 24 reciproeated by means of a main drive portion of the machine. The lower end of this rod is rotatably connected to a crank arm 25 which is rigidly connected to a rotatably mounted crank rod 26. This crank rod which is rotatably mounted in bearings 27 carries a pair of spaced substantially vertical crank arms 28' and 29 rockable with the crank rod 26. These arms carry on their upper ends a yoke 30 and the feed dogs 22. This yoke 30 embraces a cam 31 mounted for rotation with a driven shaft 32.

With this arrangement the rocking of the shaft 26 from the reciprocal rod 24 causes reciprocating arcuate movement of the crank arms 28 and 29 and back and forth movement of the feed dogs 22. The cam 31 en'- gaging the yoke 30 causes up and down movement of the feed dogs 22; Thus, as is customary in sewing machines of this type, the feed dogs in feeding material forwardly through the'machine are driven forwardly by forward reciprocation of the arms 28' and 29', downwardly by operation of the cam 31, rearwardly by reverse reciprocation of the arms 28 and 29', upwardly by means of the vided' with a thread engaging beak 34 and the usual leopcasting tail 35 adapted to engage thread from the needle 20 when the needle is in the position shown in the draw- 3 ings and draw the thread around the loop taker 33 before casting it about the bobbin thread.

The bobbin thread is wound on a bobbin 36 that is confined within the bobbin case 37. This bobbin case comprises a cup-shaped body section 38 held within the loop taker 33 by means of a circumferential rib 38a held within a similarly shaped groove 33a in the loop taker. This body section 38 is provided with an upwardly extending finger 38b received in an opening within a spring strip 39 in order to prevent rotation of the bobbin case when the loop taker is rotated. Thus, as is shown in Figure 2, this finger 38b is adapted to press against a spring piece 40 mounted on the spring strip 39. Again this action is similar to that commonly employed in sewing machines of this type. In Figure 2 the spring strip 39 is shown broken away for clarity of illustration.

In order to cooperate with the body section 38 in retaining the bobbin 36 within the bobbin case there is also provided a cap section 41 telescopically received within the body section 38. This cap section 41 is provided with an end part 41a and a cylindrical side part 41b. The engagement of the shoulder 41c on the cap section with a similar shoulder formed in the inner edge of the rib 38a on the body section 38 limits the extent of inward telescoping movement of the cap section 41.

In order to removably latch the body section 38 and cap section 41 together there is provided a snap-acting spring catch member on one section cooperating with a catch receiving portion in the other section for removably connecting these sections together. In the embodiment shown in Figures 1 to inclusive this spring catch member comprises a stud 42 mounted at substantially the center of the end part 41a of the cap section as by being screwed therein and extending inwardly of the bobbin case. For a portion of the length of this stud from the inner end thereof the stud is split into four parts by longitudinal grooves 42a. The resulting sections 42b are springable toward and away from each other by reason of the resiliency of the steel of which the stud is made.

The free end of the stud 42 is beveled outwardly as indicated at 420 so as to snap into an opening 38c in the base of the body member 38 positioned substantially centrally thereof. Thus the snap-action caused by the springiness of the free end of the stud 42 and the engagement of the beveled end thereof with the opening 38c serves to retain the cap section 41 in position. Furthermore this stud 42 serves as a mounting for the bobbin 36 so that the bobbin is rotatable therearound when thread is withdrawn from this bobbin.

With this construction just described the two parts of the bobbin case, the body section 38 and cap section 41, are retained firmly in engagement while permitting rotation of the bobbin 36. When it is desired to remove the bobbin 36, the end part 41a of the cap section may be grasped at the transverse part 41d and the cap section pulled outwardly. This snaps the sections 42b from engagement with the opening 380 so that the cap section 41 may be removed with the bobbin 36 and a new filled bobbin placed on the stud 42. Actually in removing the cap section 41 it is only necessary to insert one finger down through the opening left by removal of the access plate 43, grasp the bottom of the transverse part 41d and pull upwardly. Because of the considerable length of the stud 42, this upward pull provides leverage on the bottom part of the stud to disengage this bottom part and thus the entire stud from the opening 380.

As can be seen most clearly in Figure 4 the contacting surfaces of the side or rim portion 41b of the cap section 41 and the rim portion of the body section 38 are curved inwardly toward the body section base portion to provide ball-shaped surfaces so that pressure on the cap section 41 in a direction laterally to the central axis of the stud 42 causes tilting of the cap section 41 relative to the body section. This tilting which is permitted by the ball-Shaped engaging surfaces results in a leverage ill being exerted on the inner end of the stud 42 in order to snap this split inner end from within the opening 389. The cap section 41 being thus released is then readily removable to permit insertion of a fresh bobbin. In the embodiment shown, this transverse pressure is most easily accomplished by the operator of the machine grasping the bottom of the transverse part 41d, as shown most clearly in Figures 2 and 3, and pulling upwardly on the cap section 41.

In the embodiment shown in Figures 6 and 7 the cupshaped body section 38 is provided with an outwardly extending stud 50 divided similarly by transverse splits into four spring parts 50a. These parts are similarly outwardly beveled as indicated at 50b and engage an opening 51a of a tube 51. This tube is attached to the end part 41a of the cap section 41 and telescopically receives the stud 59. In this embodiment the bobbin 36 is rotatable on the tube 51 which receives the stud 50. Here again the cap section 41 may be easily removed to remove the bobbin 36 for replacement thereof by merely pulling outwardly on the cap section. This is most easily accomplished by grasping the transverse part 41d with the finger and thumb to exert the outward force thereon.

The bobbin case of this invention provides a structure wherein the cap section is firmly retained in place on the body section during the sewing operation. However, when it becomes necessary to remove the bobbin case, this is easily done by merely grasping the cap section and pulling outwardly thereon due to the snap-action of the latch mechanism. With the structure of this invention the cap section is automatically positioned properly so that the bobbin will be neither too loose to trap thread or rattle nor bound so tightly that the thread is pulled unevenly from the bobbin. Furthermore, the diameter of the portion on which the bobbin is rotatably mounted may be easily controlled to hold the bobbin with the right amount of resistance to rotation.

The outward dimensions of the spring portions of the stud 42 or 50 and thus the force required to engage and disengage the stud with this opening may be easily regulated if desired. Thus one manner of accomplishing this adjustment is illustrated in the embodiment shown in Figures 1 to 5. In this embodiment the central opening is threaded, as illustrated at 42d, and is provided with a screw 45 which may be positioned inwardly to force the sections 42b further apart or partially removed to permit the parts to spring closer together.

Having described my invention as related to the embodiments set out herein, it is my intention that the invention be not limited by any of the details of description unless otherwise specified, but rather be construed broadly within its spirit and scope as set out in the accompanying claim.

I claim:

In a sewing machine, a bobbin case, comprising: a cupshaped body section including a base portion and a generally circular rim portion extending therefrom, the base portion having a substantially centrally located opening therein; a cap section including a base portion and a generally circular rim portion extending therefrom which cap section rim portion is of considerably greater depth than the rim on the base portion of the cup-shaped body section and having an outer free end portion which is of substantially the same depth as the said rim portion on the cup-shaped body section, and telescopically received within the body section rim portion when said sections are assembled and bearing thereagainst, the base portions of said body and cap sections being normally spaced apart to define a bobbin-receiving space; and a substantially centrally located bobbin-receiving axial stud on the cap section base portion having its inner end wedged within the sides of said opening when the sections are assembled in said telescoping relationship, said inner end being split into a plurality of spaced parts springable toward each other in engaging and disengaging said inner stud end with the sides of said opening, the bearing surfaces of said rim portions of the body and cap sections being curved inwardly toward said body section base portion to provide ball-shaped surfaces whereby pressure on the cap section in a direction laterally to the central axis of said stud causes tilting of the cap section relative to the body section with resulting leverage on said inner end of the stud to snap said inner end from said opening.

267,020 Roberts Nov. 7, 1882 6 Heberling July 27, Wardwell Dec. 3, Diehl Mar. 20, Bates Mar. 8, Nelson May 30, Hayes Sept. 16, Collins Jan. 8,

FOREIGN PATENTS Germany Jan. 14, 

